Acetonitrile is the chemical compound with the formula CH3CN. This colourless liquid is the simplest organic nitrile. It is produced mainly as a by-product of acrylonitrile manufacture.  Acetonitrile is very soluble in water and mixes with most organic solvents, e.g. alcohols, esters, acetone, ether, benzene, chloroform, carbon tetrachloride and many unsaturated hydrocarbons. It does not mix with petroleum ether and many saturated hydrocarbons. Acetonitrile is incompatible with water, acids, bases, oleum, perchlorates, nitrating agents, reducing agents and alkali metals. Acetonitrile decomposes on contact with acids, water and steam, producing toxic fumes and flammable vapour. It reacts with strong oxidants such as nitric acid, chromic acid and sodium peroxide, causing fire and explosion hazards. Acetonitrile forms toxic fumes of hydrogen cyanide and nitrogen oxides on combustion. It attacks some forms of plastics, rubber and coatings. 
Acetonitrile is predominantly used as a solvent in the manufacture of pharmaceuticals, for spinning fibres and for casting and moulding of plastic materials, in lithium batteries, for the extraction of fatty acids from animal and vegetable oils, and in chemical laboratories for the detection of materials such as pesticide residues. In addition, acetonitrile is used in dyeing textiles and in coating compositions as a stabiliser for chlorinated solvents and in perfume production as a chemical intermediate.
Sources & Routes of Exposure [2,3]
Sources & Potential Exposure
Sources of acetonitrile emissions into the air include:
- Manufacturing and industrial facilities;
- Automobile exhaust; and
- Volatilisation from aquatic environments.
- Individuals may be exposed to acetonitrile through breathing contaminated air, from smoking tobacco or proximity to someone who is smoking; or
- Through skin contact in the workplace.
Routes of Exposure
The main routes of exposure to acetonitrile are via the inhalation of vapours and contact with the skin and eyes. Absorption through intact skin occurs rapidly. Ingestion is an unlikely route of exposure.
Health Effects 
- Concentrations up to 500 parts per million (ppm) acetonitrile through inhalation exposure cause irritation of mucous membranes in humans, and higher concentrations can produce weakness, nausea, and convulsions.
- Tests involving acute exposure of rats, mice, rabbits, cats, and guinea pigs have shown acetonitrile to have moderate to high acute toxicity from oral exposure and moderate acute toxicity from inhalation exposure.
- Chronic inhalation exposure of humans to acetonitrile results in cyanide poisoning from metabolic release of cyanide after absorption. The major effects consist of those on the central nervous system (CNS), such as headaches, numbness, and tremor.
- Cyanide poisoning can also be produced through the ingestion of acetonitrile or from contact with the skin.
- Application of acetonitrile to the skin may produce dermatitis in humans.
- Animal studies have shown that different species vary widely in susceptibility to acetonitrile by various routes.
- EPA has not established a Reference Dose (RfD) for acetonitrile.
- The Reference Concentration (RfC) for acetonitrile is 0.06 milligrams per cubic metre (mg/m3) based on mortality in mice.
- No information is available on the reproductive or developmental effects of acetonitrile in humans.
- Animal studies appear to suggest that acetonitrile may cause developmental and reproductive effects such as a decrease in average foetal body weight and a significant increase in the number of malformed offspring.
- No pertinent data concerning the carcinogenicity of acetonitrile in humans were located.
- The National Toxicology Program (NTP) completed a 2-year carcinogenesis inhalation study on acetonitrile and concluded that there was equivocal evidence of carcinogenicity in male rats, and no evidence in male or female mice or in female rats.
- EPA has classified acetonitrile as a Group D, not classifiable as to human carcinogenicity.
First Aid Measures
- Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used. Get medical attention.
- Skin Contact: In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover the irritated skin with an emollient. Cold water may be used. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention immediately.
- Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention.
- Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.
- Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive. Seek immediate medical attention.
- Ingestion: If swallowed, do not induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing such as a collar, tie, belt or waistband. Get medical attention immediately.
Acetonitrile is highly flammable in presence of open flames, sparks of heat and oxidising materials. In the case of a small fire dry chemical powder should be used to extinguish. For large fires, use alcohol foam, water spray or fog.
Exposure Controls & Personal Protection
- When using acetonitrile, exhaust ventilation or other engineering controls should be used to keep the airborne concentrations of vapours below their respective threshold limit value.
- Eyewash stations and safety showers should be located proximal to the work-station.
Personal Protective Equipment
When handling acetonitrile the following personal protective equipment is recommended:
- Splash goggles;
- Lab coat;
- Vapour respirator (be sure to use an approved/certified respirator or equivalent);
Personal Protection in Case of a Large Spill:
- Splash goggles;
- Full suit;
- Vapour respirator;
- A self contained breathing apparatus should be used to avoid inhalation of the product.
- Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.
Exposure Limits [2,5]
- OSHA: The Occupational Safety & Health Administration has established a Permissible Exposure Limit (PEL) for acetonitrile of 40 ppm, 70 mg/m3 TWA
- ACGIH: The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) is 20 ppm, 34 mg/m3 TWA; Skin; Appendix A4 – Not Classifiable as a Human Carcinogen
- NIOSH: The National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)is 20 ppm, 34 mg/m3 TWA
- Safe Work Australia: Safe Work Australia has established an exposure standard for acetonitrile of 40 ppm (equivalent to 67 milligram/m3) (TWA). The short-term exposure level (STEL) is 60 ppm (equivalent to 101 milligram/m3). Safe Work Australia also issued a skin absorption notice, which indicates that absorption through the skin may be a significant source of exposure.